Can Evolution Evolve?
Feb 16, 2007
When the Soviet Union dissolved almost twenty years ago Francis Fukuyama equated the rise of neoliberal capitalism with the "end of history." He claimed society had progressed to the highest forms of government and market possible, achieving "the end point of mankind's ideological evolution and the universalization of Western liberal democracy as the final form of human government," (Fukuyama, 1989). The age of globalization that followed Fukuyama's statement disproved his thesis to the point where he himself had to rescind his comments[i]. However, today there seems to be a similar sentiment growing that the advent of medical technology has made the end of human evolution imminent. While this idea lays its foundations in more sound observations, it remains a specious argument based on an incomplete set of observations.
The thesis that human evolution is ending is tied to our ability to evade natural selection. In his book, What Evolution Is, Ernst Mayr provides a valuable breakdown of the basic principles of evolution[ii]: all species are fertile enough that, without an environmental constraint, they will replicate at an exponential rate. A combination of factors that limit the probability of survival, such as intense competition over limited resources and genetic characteristics that aid the individual’s survival in a given environment, all keep population increases in check. Mayr concludes the final observation as, “Fact 5: Many of the differences among the individuals of a population are heritable; Inference 3: Natural selection, continued over many generations, results in evolution," (Mayr, 116). Darwin defined evolution as the product of natural selection taking place over the course of generations. Mayr further explores natural selection,
"Every species produces vastly more offspring than can survive from generation to generation... They are exposed to the adversity of the environment, and almost all of them perish... However, the survivors are not a random sample of the population; their survival was aided by the possession of certain attributes that favor survival... what Darwin called natural selection is actually a process of elimination," (Mayr, 117).
While Mayr notes that natural selection is not actually a 'selection of the fittest,' rather than the elimination of the least fit to survive, he claims elimination is necessary for evolution. "Those individuals who are most efficient in coping with the challenges of the environment and in [competing] will have the best chance to survive until the age of reproduction and to reproduce successfully... Certain individuals with particular attributes are clearly superior to others during this process of elimination," (Mayr, 119-120). This gives rise to a few questions.
Accepting that elimination is a necessary step of evolution, has the process been halted or encumbered by increased human control over survival? With the advent of medical technology, humans are now capable of 'artificially' preventing disease, prolonging life, and enabling reproduction for those who would not previously have been able to pass on their genes. In an article titled "Becoming Genomic," Glenn McGee argues that understanding heritability through the mapping of the human genome "represents the most significant shift in our lifestyle since the adoption of personal computers," and is "a shift in how we see ourselves, our potential, our families, and our society... My genes will soon fit on a digital chip in my wallet, so clinicians can easily refer to it when I get sick," (McGee, 2001). Not only could McGee's digital chip help pinpoint a disease when he gets sick, it might prevent him from getting sick in the first place. "Ten years ago it would have been unthinkable for a healthy woman to remove her breasts because her mother had breast cancer. Today a genetic aberration is often the most real thing about a disease... Society has moved from medicine based on disease to [prevention]. Understanding how your genome puts you at risk will be critical to being genomic," (McGee, 2001). Arthur L. Caplan takes this thinking one step further in examining germline interventions. “[H]ereditary information which is of value, not for the individual but for the species, may be lost,” by interfering with the genetic makeup of a fetus– something that would not happen with natural evolution. However, he claims “At best, genetic diversity is an argument for creating a gamete bank to preserve diversity. It is hard to see why an unborn child has any obligation to preserve the genetic diversity of the species at the price of grave harm or certain death,” (Caplan, 2002). He does not debate that human advances in understanding and shaping hereditability will affect evolution. Rather, he claims that such an effect is desirable and its negative aspects negotiable.
What is missing from these articles is the limitation of these advancements. “Despite the medical advances and comforts that shelter people in rich countries, natural selection is still at work. Microbes and parasites still nip at our heels, forcing the human genome to stay in constant motion. It is clearly in the throes of adapting to malaria…and the protective gene that has sickle cell anemia as a side effect is a sign of a hasty patch,” (Wade, 2003). Furthermore, in an increasingly mobile world, gene flows have also expanded. A founder of population genetics (and supporter of eugenics), Ronald Fisher, “argued that large populations with random mating -- just what globalization and air travel are helping to bring about -- were the best fodder for rapid evolution,” (Wade, 2003). Mayr would probably agree with Fisher, “Surely when a population suddenly encounters an extremely adverse situation, the more genetically diverse it is, the greater is the chance that it contains genotypes that can better cope with environmental demands,” (Mayr, 105). This implies that increased migration, such as in today’s world, would reinvigorate evolution and combat any lulls caused by increased control over the process.
Such an acceleration is certainly needed. The migrations do not stop with people: diseases are also traveling. While we (or at least some of us, the chip McGee mentions costs about $1,000) may be able to alter our genetic makeup, our environment is also evolving. Global Climate Change has made it possible for malaria-carrying mosquitoes to live in higher altitudes and for birds carrying the Avian Flu to migrate to areas in North America they had never seen before. The irony here is that wealthy nations, where humans have the highest level of self-determination in the process of evolution and where most of this debate is centered, have exponentially altered their environments.
In this regard, Wade vastly underestimates the impact of the changes he mentions on evolution, “It seems reasonable to predict that the human physical form will stay in equilibrium with its surroundings. If the ozone layer thins, pale skins will be out and dark skins de rigeur. If climate heats up, the adaptations for living in hot places will spread.” Despite his confidence he acknowledges “it could take tens or hundreds of generations for a new gene to become widespread,” (Wade, 2003). Seeing as malaria has existed for roughly 8,000 years and humans have not evolved past it, it is clear that such drastic changes in the environment will severely test our ability to survive.
Humans are not the sole actors in the process of our evolution. Since we are dependent on resources and our host environment for survival, their evolution deeply impacts ours. Medical advancements are not enough to make evolution irrelevant.
[i] Ironically, Fukuyama now claims “as a result of biomedical advances, we are facing the possibility of a future in which our humanity itself will be altered beyond recognition… that the ability to manipulate the DNA of all of one person's descendants will have profound, and potentially terrible, consequences for our political order, even if undertaken with the best of intentions,” (Abstract of Fukuyama, 2002).
[ii] "Fact 1: Every population has such high fertility that size will increase exponentially if not constrained. Fact 2: The size of populations... remains stable over time. Fact 3: The resources available to every species are limited; Inference 1: There is intense competition... Fact 4: No two individuals... are exactly the same; Inference 2: Individuals differ from each other in the probability of survival. Fact 5: Many of the differences among the individuals of a population are heritable; Inference 3: Natural selection, continued over many generations, results in evolution," (Mayr, 116).
1. Balter, Michael. Tick, Tock: Humans Have a Slow Molecular Clock. ScienceNOW Daily News, January 23, 2006.
2. Calplan, Arthur L. If Gene Therapy is the Cure, What is the Disease? The American Journal of Bioethics at bioethics.net, November 8, 2002.
3. Fukuyama, Francis. The End of History? The National Interest, Summer 1989.
4. --- Our Posthuman Future: Consequences of the Biotechnology Revolution. Farrar Straus & Giroux: Picador 2003
5. Mayr, Ernst. What Evolution Is. Basic Books: New York, 2001.
6. McGee, Glenn. Becoming Genomic. The American Journal of Bioethics at bioethics.net, February 10, 2001.
7. Wade, Nicholas. Can It Be? The End of Evolution? The New York Times, August 24, 2003.